The deleterious effects of fog and low stratus on military activities are well known. Any capability to modify unfavorable weather has potential benefits for many segments of the military and civilian community. Research and development activities to modify warm fog have been conducted for more than three decades. The classical works with sprayed calcium chloride solution pointed a way to fog clearance. Nevertheless, the concepts of hygroscopic treatment of dry fog were not sufficiently developed in ensuing years to generate a reliable system. During World War II the heavy traffic of military aircraft at fog-bound bases in the United Kingdom led to the development and use of drying by thermal systems the direct application of the heat of combustion of petroleum fuels. Although this method did clear fog, there are many drawbacks, including immobility, cost, maintenance, pollution by smoke and water vapor, and the hazards of open flames near runways. The use of jet engines as a heat source has also been tested with varying results in warm fog. Although engineering developments might remove some of the drawbacks of a thermal system, one fundamental limitation remains. Each site where fog clearance is needed would require its own installation. Under most tactical conditions in the field, a capability is needed to take the treatment to the fog. A number of pyrotechnics generating ice nuclei have been developed for modifying cold clouds and cold fogs, also chemical smokes which theory suggests may have effects in warm clouds and fogs. The pyrotechnics used were of two general types: (1) airborne fused units, which are electrically fired and burned in place in a horizontal rack mounted behind the aircraft wing; and (2) large cylindrical units, which are burned on the ground. The present invention provides a method for injecting seeding nuclei of hygroscopic liquids into warm fog and stratus to give operationally useful clearings whereby an aircraft could take off or land.